With President Joe Biden still refusing to limit American support for Israel’s bloody offensive in Gaza, senators could soon play a big role in challenging — and even changing — the U.S.’s deeply controversial approach.

Sen. Bernie Sanders (I-Vt.) has scheduled a Tuesday evening Senate vote on a resolution requiring the Biden administration to produce a report on Israel’s human rights practices. Israel is currently targeting areas where Palestinians fled for safety while experts are ratcheting up warnings of famine among Gazans.

Sanders’ bill is privileged, meaning Senate leadership has to allow it to be considered, opening up a rare chance for senators to extensively debate Israel’s Gaza campaign.

Meanwhile, Sens. Chris Van Hollen (D-Md.) and Tim Kaine (D-Va.) are championing amendments to a potential supplemental package of military aid for Israel and Ukraine that would both, if passed, represent rebukes to the idea of unquestioned assistance to Israel. Van Hollen’s proposal underscores that American military aid must be used in line with international and U.S. law, while Kaine’s bill would force Biden to maintain the normal process of informing Congress about U.S. weapons shipments for Israel; he has recently twice used emergency authority to circumvent oversight.

The Sanders effort is becoming the chief focus of attention among lawmakers, their staff and prominent outside advocates because the resolution will be voted on so soon.

Members of Congress overwhelmingly support Israel’s intention to punish the Gaza-based militant group Hamas and its partners for a brutal surprise Oct. 7 attack that killed 1,200 Israelis and led to more than 200 being taken hostage. But Israel’s conduct since — which has killed upwards of 23,000 people and entailed scores of alleged war crimes — has horrified many legislators and led to public calls for a change in policy from a significant number of Democrats. More than 60 Democratic lawmakers now support a cease-fire in the Israel-Hamas war, and elected officials say they feel major public pressure to do more to ease Gaza’s suffering.

Sanders and some other legislators say it’s past time for Capitol Hill to turn concern into action, as a signal to both Israel and the Biden administration, which despite its claims of encouraging Israeli restraint has taken no tangible steps to force it.

A human rights report would provide one way for Congress to scrutinize what the U.S. knows about Israel’s conduct and whether national security experts within the government — a number of whom have told HuffPost they feel muzzled and sidelined — agree with outside analysts who call the campaign excessive and counterproductive.

On Thursday, a coalition of 75 advocacy groups launched an effort to rally senators to vote for the Sanders bill, sending legislators a letter exclusively shared with HuffPost ahead of its release.

“After months of devastation in Gaza, there is urgent need for a meaningful debate on U.S. support for Israeli operations … including the extent to which U.S. military aid may be supporting violations of international human rights and humanitarian law,” reads the letter, signed by organizations ranging from Amnesty International and Indivisible to Jewish, Muslim and Christian groups. “It is long overdue for the Senate to hold a public vote and debate on U.S. complicity in Israeli human rights abuses against Palestinians living under occupation and bombardment, and to reassert congressional oversight powers over U.S. arms transfer policy and foreign policy.”

For now, the State Department says it is not assessing whether Israel is following international humanitarian law, and it’s not even publicly clear how seriously Biden’s team is holding the country to its own policies on weapons exports, while officials within the agency describe confusion about what assessments are underway.

A State Department spokesperson provided comment for this story after publication on Thursday morning.

The spokesperson claimed State is evaluating weapons transfers to Israel in line with Biden’s standard that they cannot be permitted if it is “more likely than not” such weapons will be used to break international law. State has not made any determinations related to potential war crimes in Gaza, the spokesperson said, writing: “We are monitoring this evolving situation and are examining facts as they develop.”

State is “fully committed” to holding Israel accountable under the so-called Leahy law, which is intended to bar U.S. military aid for foreign military units who commit rights abuses, the spokesperson added. Current and former State Department officials say Israel has always received special treatment in Leahy probes, however, and Washington has declined to halt assistance even to units with clear records of abuses, like the Israeli military’s Netzah Yehuda battalion.

And the spokesperson ignored a query on whether State is assessing if Israel’s slow-rolling of humanitarian aid for Gaza violates a U.S. law barring arms sales to countries blocking relief efforts, which some U.S. officials suspect to be the case.

“The United States, whether we like it or not, is deeply complicit in what is going on in Gaza right now: Those are our weapons that are killing children in huge numbers, that are destroying homes in huge numbers ... that are resulting in the hunger, the lack of medical care that the people of Gaza are now experiencing,” Sanders said on Wednesday. “I don’t think there’s any debate in Congress that Israel has the right to live in peace and security ... I do not believe we are doing Israel any favors by ignoring what their policies are doing right now.”

An Overdue Conversation

The Sanders bill relies on an often overlooked provision in the Foreign Assistance Act: Section 502b, which lets lawmakers request a State Department report on the human rights practices of a country receiving American military assistance.

Regardless of whether the legislation passes and mandates that report, its supporters say it’s vital to open a discussion in the Senate.

“This is important to spotlight human rights abuses, get media attention and force senators to get on the record one way or the other on whether or not they support scrutiny of Israel’s conduct,” said Hassan El-Tayyab of the Friends National Committee on Legislation, a Quaker peace group. “Unless members [of Congress] are actually forced to vote and debate on something, they’re not really digging too deeply into any issue. When staffers have to put a vote recommendation up to a member, that’s when they’re writing policy memos … they haven’t ever been forced to do that on anything supporting Palestinian rights.”

Backers of the bid are also betting they can win a striking level of support when the vote occurs. The majority of Senate Democrats have already signed a statement urging Biden to explain what the U.S. is doing to shield civilians in Gaza and provide an assessment of whether Israel’s operation is abiding by American military norms. Some Senate offices are already quietly leaning toward voting with Sanders, a Democratic aide told HuffPost.

Sanders on Wednesday emphasized that supporting his bill would not mean “cutting one nickel of aid to Israel.”

“This is not a controversial resolution. Every one of us should want to know whether our U.S. military aid is being used in violation of international law or not, no matter what your view of the war may be,” the senator argued.

Still, anything relating to Israel “is still very controversial” on Capitol Hill, the aide said. Ardently pro-Israel activists are likely to rally skepticism among senators.

Asked about their positions by HuffPost this week, three senators demonstrated how the Sanders bill faces an uphill battle. Sens. Dick Durbin (D-Ill.) and Chris Murphy (D-Conn.) — two of the lawmakers who have so far been more willing to question the Israeli campaign in Gaza — said they have not read the legislation yet. And Kaine, an influential voice on national security, said he is “not inclined to support” the Sanders gambit.

“There’s some elements of it that, language-wise, go a little farther than I feel comfortable with,” Kaine told HuffPost, noting he supports other congressional attempts to probe U.S. aid for Israel.

The resolution includes references to reports on Israeli actions like using 2,000-pound bombs, and to Israel’s crackdown beyond Gaza in the occupied West Bank, where 2023 was the deadliest year for Palestinians on record.

Supporters of the Sanders bill say that helps ensure a meaningful conversation.

“The text does include good context to understand where the need for this reporting and this debate is coming from,” said John Ramming Chappell of the Center for Civilians in Conflict. “By appealing to a number of credible sources on these issues, I think the Sanders resolution is able to frame the debate in ways that are productive.”

Whatever the bill’s fate, observers say the gambit will represent a significant step for Congress.

If senators do vote to request the report, which they could do without needing approval from the Republican-controlled House or the president, the Biden administration would be under significant pressure.

“Their attitude thus far has been, ‘Nothing to see here,’” said former State Department attorney Brian Finucane, who is now with the International Crisis Group.

“It’s clear any assessments undertaken by the State Department would not be independent, they would not necessarily be objective … given the political imperative of continued military support for Israel,” Finucane continued.

Still, he sees the process of forcing a discussion as “worthy” and hopes to see it extend to questions over additional U.S. actions since Oct. 7, like military responses to groups striking American targets regionally in retaliation for America’s role in Gaza.

“The U.S. is currently playing the role of arsonist and firefighter simultaneously in the Middle East because of the White House’s unconditional support for Israel,” Finucane told HuffPost. “Congress has been missing in action in terms of asserting its own constitutional prerogatives here as the U.S. is engaged in hostilities in two theaters, neither of which has been authorized by Congress: Iraq and Syria and in the Red Sea.”

A Groundswell Of Congressional Action

With Congress back in session as of this week, lawmakers are pursuing multiple ways to show they want a change in Israel’s — and Biden’s — approach to Gaza.

If the Senate does consider the proposed supplemental bill of assistance for Israel and Ukraine, many Democrats are hopeful it will include Van Hollen’s widely backed amendment highlighting the need to adhere to international humanitarian law.

Kaine this week unveiled another possible amendment to the supplemental that would kill an attempt by the Biden administration to remove the requirement to tell Congress about some U.S. arms sales to Israel. In December, Biden twice bypassed normal weapons sales procedures to expedite weapons for the Israeli military, a step Democrats have criticized. Last week, Sen. Elizabeth Warren (D-Mass.) argued the U.S. should instead “condition aid” and “move the parties towards a lasting peace.” (Warren has long embraced the idea of conditions on American support for Israel.)

Progressive and anti-war activists want senators to see the Van Hollen, Kaine and Sanders efforts as linked rather than in competition.

“There are a lot of promising efforts in the Senate to push for greater transparency and oversight and to assess what the impact of U.S. military aid to Israel is at this time — I don’t think they are mutually exclusive,” Chappell said.

And in the House of Representatives, skeptics of Israel’s approach are hoping to secure more calls from Democratic legislators for a cease-fire in Gaza.

“If we could get to 100 people for a cease-fire in the House, that would be a big statement,” Rep. Ro Khanna (D-Calif.) said, noting he hopes to see Hamas release Israeli hostages and Gazans receive far more aid.

“The urgency is not just about the killing of civilians, but the lack of food and water,” added Khanna, drawing a parallel to the situation the U.S. helped create in Yemen in recent years.

Khanna helped lead congressional opposition to the Yemen policy, which ultimately forced shifts in policy from Biden and former President Donald Trump. “The parallel to Yemen in terms of the potential famine and starvation is correct, and the aid can’t get in effectively until there is a cease-fire,” Khanna said.

On Jan. 6, United Nations aid chief Martin Griffiths issued a statement urging an end to the war and noting: “Famine is around the corner…Gaza has shown us the worst of humanity.”

Igor Bobic contributed reporting.